The Cell Sorting Facility (CSF) offers Fox Chase Cancer Center (FCCC) investigators the capability of analyzing single cell suspensions by up to 14 independent measurements, 12 of which are based on immunofluorescence and two on light scattering. In calendar year 2009 the Facility was used by 31 peer-reviewed, funded investigators across four of the five CCSG Research Programs. The large majority of Facility usage (98.5%) was by peer-reviewed, funded investigators. Major applications of flow cytometry include discrimination and isolation (sorting) of cell subpopulations (at up to 20,000 cells/sec), isolation of rare variant (1/10'') cell subsets, characterization of tumors or cell lines, and single cell cloning of cell subpopulations by direct deposition into 96-well plates. The current sorter provides high-speed 4-stream sorting and digital detection. A UV-capable laser enables measurement of calcium flux and viable cell DNA content. In addition to the 3-laser 12-color cell sorter (FACS-VantageSE/DiVa), the Facility also includes an analysis-only 10-color LSR-II and a 3-color FACScan. In 2009 the Center provided funds ($240,000) for a new Bay Biosystems JSAN desktop cell sorter. The user-operated JSAN is capable of up to 8-color 2-stream sorting and utilizes 3-beam excitation with flow-cell detection, including a UV laser. The Facility aids users with advice on experimental design (including availability of reagents and appropriate fluorochromes), sample preparation, and data interpretation. Software developed with the FCCC Biostatistics and Bioinformatics Facility (BBF), the Flow-LIMS, is used for data annotation, organization, and archiving. Analysis is done on investigators'laboratory computers using a highly interactive, graphical software program, FlowJo. Hours of usage, 2,778/year (currently estimated at over 64% of theoretical capacity), has increased 34% since the last review and is projected to increase over the next five years with planned recruits across all five Programs, Hardy (Immune Cell Development and Host Defense (ICDHD) Program), has directed this resource since 1987 and has responsibility for Facility operations. Equitable access to the Facility is assured by Facility policy, oversight from a Facility Advisory Committee (FAC) and a governing Facilities Parent Oversight Committee (FPOC).